A wide range of designs of flow-controllable cell pumps with pivotable control slide valves such as for example flow-controllable vane cells pumps or also flow-controllable pendulum slide valve machines are pre-described in the prior art.
For example DE 44 42 083 C2 describes a vane cell pump with variable delivery output with a hinge pin/bolt mounted in the front and the rear cover about which the control slide valve is mounted in a pivotable manner.
In the covers of this flow-controllable cell pump on both sides of the rotor a suction kidney on the one side and offset from the latter by 180° a pressure kidney is arranged on the other side. A defined inflow from the suction connection in the suction kidneys as well as a defined discharge of the pump volumetric flow from the pressure kidneys into the pressure connection is guaranteed through connecting channels which are provided in the covers, i.e. cast in the covers mostly manufactured of aluminium casting.
The manufacture of these covers with integrated connecting channels is very production-intensive and consequently also very high-cost.
Added to this in the manufacture of the covers of aluminium casting, wherein for smaller series mostly the sand casting method is employed (a production-intensive and consequently also very high-cost method) is employed, that these connecting channels produced by the sand casting method possess an increased surface roughness due to the manufacturing method.
This increased surface roughness of the connecting channels inaccessible for effective reworking then when used in operation brings about increased flow and efficiency losses as a matter of course.
A further disadvantage of these designs when used for the lubricating oil supply of a combustion engine also consists in that in the upper rotational speed range, vibrations occur on the control slide valve, which subsequently cause pressure pulsations.
On the part of the inventor, a plurality of controllable cell pumps meanwhile proven in practice and likewise provided with a pivotable control slide valve have been presented. Mostly in the design of pendulum slide valve machines.
For example EP 1 225 337 B1 describes a flow-controllable cell pump likewise provided with a control slide valve, wherein the control slide valve is pivotably mounted in the pump housing either by means of a bearing bolt arranged in the housing or by means of a bearing eye moulded on to the control slide valve, which becomes operationally connected with a guide ring groove arranged in the housing.
With these solutions, the connecting channels are mostly arranged directly in the control slide valve, i.e. either directly in the bearing eye or near the bearing seat of the bearing bolt in the control slide valve.
Such designs wherein connecting channels are directly arranged in the control slide valve are highly suitable for larger lot sizes since the connecting channels, which are complicated to manufacture and are arranged between the two sides of the cell pump in the pump housing, fall away.
A disadvantage also of these aforementioned solutions results from the space required for these solutions in order to guarantee the stability of the individual assemblies of the pumps in the operating state.
Here, the permissible surface pressure on the bearing seat greatly restricts both the dimensioning of the bearing as well as the selection of the material for the control slide valve.
From DE 33 34 919 C2 a further possibility of mounting a pivotable control slide valve has become known.
Here, on both the control slide valve as well as in the pump housing a ball guide each or a bearing shell for accommodating (i.e. between the ball guide/bearing shell of the control slide valve and the ball guide/bearing shell of the pump housing) an associated bearing ball (or as already explained an associated bearing bolt) is arranged.
The region between the housing and the control slide valve is sealed through spring-loaded sealing bolts as presented in DE 33 34 919 C2, so that there can be flow around the region surrounding the bearing ball or the bearing bolt.
The arrangement of such spring-loaded sealing bolts between the housing and the control slide valve however is likewise highly production-intensive and high-cost, wherein however when using a bearing ball the dimensioning of the associated bearing and also the selection of the material for the control slide valve is severely restricted.
In DE 10 2006 061 326 a pivotable mounting of a control slide valve in the pump housing is pre-described among other things on the part of the inventor of the solution present here, wherein on the control slide valve as well as in the pump housing a bearing shell each for the joint accommodation of an associated bearing bolt is arranged.
Near the bearing shell of the bearing bolt a through-flow opening/connecting channel is arranged in the control slide valve (as is usual in the prior art).
This connecting channel arranged near the bearing seat of the bearing bolt in the control slide valve in this case can be optimally sealed by the control slide valve proper, but results in that the size of the pump is increased as a matter of course through the need for the connecting channel. With all aforementioned pumps unavoidable running noises currently occur in the operating state which are the result of the force vector from the drive power of the pump always being directed at the fulcrum/the bearing bolt so that the pressure peaks which result from the emptying of the individual cells lead to these pressure peaks being transmitted as vibrations via the bearing bolt to the housing and are thus also perceived acoustically.